A method for selectively hydrogenating acetylene in a cracked gas from a steam cracking unit for producing olefins may include separating a hydrogenation feed from the cracked gas. The hydrogenation feed may include acetylene, hydrogen, carbon monoxide, and at least one product. The method may further include contacting the hydrogenation feed with an acetylene hydrogenation catalyst, the contacting causing hydrogenation of at least a portion of the acetylene of the hydrogenation feed to produce a hydrogenation effluent. In response to a change in a composition of a feedstock to the steam cracking unit that results in a change in a hydrogen concentration in the hydrogenation feed, the method may further include determining the hydrogen concentration in the hydrogenation feed and increasing or decreasing a temperature of the hydrogenation feed based on the determined hydrogen concentration of the hydrogenation feed.

A method for selectively hydrogenating acetylene in a cracked gas from a steam cracking unit for producing olefins may include separating a hydrogenation feed from the cracked gas. The hydrogenation feed may include acetylene, hydrogen, carbon monoxide, and at least one product. The method may further include contacting the hydrogenation feed with an acetylene hydrogenation catalyst, the contacting causing hydrogenation of at least a portion of the acetylene of the hydrogenation feed to produce a hydrogenation effluent. In response to a change in a composition of a feedstock to the steam cracking unit that results in a change in a hydrogen concentration in the hydrogenation feed, the method may further include determining the hydrogen concentration in the hydrogenation feed and increasing or decreasing a temperature of the hydrogenation feed based on the determined hydrogen concentration of the hydrogenation feed.

A process (100, 200, 300) for the production of ethylene is proposed in which a first feed gas (A) and a second feed gas (B) are fed to a reactor (1) and processed therein by vapour cracking to obtain a product mixture (C), the first feed gas (A) comprising more than 90 weight percent saturated hydrocarbons and more than 80 weight percent ethane, and wherein the product mixture (C) or a part thereof is subjected to a treatment (2, 3, 4) and the resulting mixture (F) or a part thereof is subjected to a separation (10) to obtain a resulting mixture (F) containing hydrogen, methane, ethane, ethylene and hydrocarbons having three, four and at least five carbon atoms. The separation (10) being provided in that it comprises an ethylene separation step (7) to which at least the ethane, the ethylene and the hydrocarbons having three carbon atoms from the succeeding mixture (F) or a part thereof are fed unseparated from each other in a common separation insert (S, V, X), in which in the ethylene separation step (7) a light fraction (K) containing more than 95 mole percent ethylene is fed, and a heavy fraction (T, W, Y) containing at least a portion of the ethane from the separation insert (S, V, X) and at least 15% by weight of the hydrocarbons having three and four carbon atoms from the separation insert (S, V, X), and wherein the heavy separation product (T, W, Y) from the ethylene separation step (7) or a portion thereof is used as part or to form the second feed gas (B). A corresponding annex is also the subject of this invention.

A process (100, 200, 300) for the production of ethylene is proposed in which a first feed gas (A) and a second feed gas (B) are fed to a reactor (1) and processed therein by vapour cracking to obtain a product mixture (C), the first feed gas (A) comprising more than 90 weight percent saturated hydrocarbons and more than 80 weight percent ethane, and wherein the product mixture (C) or a part thereof is subjected to a treatment (2, 3, 4) and the resulting mixture (F) or a part thereof is subjected to a separation (10) to obtain a resulting mixture (F) containing hydrogen, methane, ethane, ethylene and hydrocarbons having three, four and at least five carbon atoms. The separation (10) being provided in that it comprises an ethylene separation step (7) to which at least the ethane, the ethylene and the hydrocarbons having three carbon atoms from the succeeding mixture (F) or a part thereof are fed unseparated from each other in a common separation insert (S, V, X), in which in the ethylene separation step (7) a light fraction (K) containing more than 95 mole percent ethylene is fed, and a heavy fraction (T, W, Y) containing at least a portion of the ethane from the separation insert (S, V, X) and at least 15% by weight of the hydrocarbons having three and four carbon atoms from the separation insert (S, V, X), and wherein the heavy separation product (T, W, Y) from the ethylene separation step (7) or a portion thereof is used as part or to form the second feed gas (B). A corresponding annex is also the subject of this invention.

A method for recovering paraxylene from a mixture of aromatic hydrocarbons. The process uses a pressure swing adsorption zone followed by a paraxylene recovery zone. The invention provides for lower throughput through the paraxylene recovery zone, resulting in lower capital costs and operating costs.

A process, a system, and an apparatus are provided for converting a lower alkane to an alkene. Oxygen and the lower alkane are provided to an ODH reactor to convert at least a portion of the lower alkane to an alkene. An ODH stream comprising the alkene, an oxygenate, steam, and a carbon-based oxide is produced. The bulk of the oxygenate is removed from the ODH outlet stream by non-dilutive cooling, with residual oxygenate being removed using dilutive quenching with a carbonate. Subsequently, separation of the carbon-based oxide from the alkene is achieved using a caustic tower, which also produces spent caustic in the form of a carbonate, which is then used as the carbonate for dilutive quenching. Dilutive quenching using a carbonate allows conversion of the oxygenate to an acetate, which can then be used to simplify separation of the oxygenate from water.

A process, a system, and an apparatus are provided for converting a lower alkane to an alkene. Oxygen and the lower alkane are provided to an ODH reactor to convert at least a portion of the lower alkane to an alkene. An ODH stream comprising the alkene, an oxygenate, steam, and a carbon-based oxide is produced. The bulk of the oxygenate is removed from the ODH outlet stream by non-dilutive cooling, with residual oxygenate being removed using dilutive quenching with a carbonate. Subsequently, separation of the carbon-based oxide from the alkene is achieved using a caustic tower, which also produces spent caustic in the form of a carbonate, which is then used as the carbonate for dilutive quenching. Dilutive quenching using a carbonate allows conversion of the oxygenate to an acetate, which can then be used to simplify separation of the oxygenate from water.

Many linear alpha olefin (LAO) syntheses form a range of LAO products when oligomerizing ethylene in the presence of a Ziegler-type catalyst. The range of products typically requires a plurality of distillation columns to separate the LAO products up to a desired carbon count, but such approaches may be energy- and capital-intensive. LAO product separation using at least one dividing wall column may lessen these burdens. Methods for separating LAOs may comprise: providing a pre-processed product stream comprising Cg+ linear alpha olefins (LAOs) to a first of a series of distillation columns, at least one member of the series of distillation columns comprising a dividing wall column; and separating an overhead stream comprising a first LAO from the dividing wall column and one or more side streams from the dividing wall column, each side stream comprising a different LAO that also differs from the first LAO.

Systems and methods for separating a mixture comprising C.sub.4 hydrocarbons and a solvent have been disclosed. The mixture is produced as a bottom stream of a rectifier column. The mixture is processed in at least two heating and flash-evaporating cycles to remove at least some C.sub.4 hydrocarbons as vapor streams. The resulted liquid stream is further degassed in a degasser column to produce a recycle vapor stream and a lean solvent stream.

Systems and methods for separating a mixture comprising C.sub.4 hydrocarbons and a solvent have been disclosed. The mixture is produced as a bottom stream of a rectifier column. The mixture is processed in at least two heating and flash-evaporating cycles to remove at least some C.sub.4 hydrocarbons as vapor streams. The resulted liquid stream is further degassed in a degasser column to produce a recycle vapor stream and a lean solvent stream.